Mechanic's creepers include a frame which carry a pad and which is supported by casters to render the creeper mobile. The frame most often includes side rails which carry the casters and a plurality of crossrails which extend between the side rails and which carry the pad.
Heretofore, most all of the rails, including the side rails, have either been of a round or a square profile. The round profile provides a degree of comfort to the user, but it is very difficult to mount casters to the round configuration. Moreover, in addition to being difficult to mount, the connection leads to maintenance problems in that the casters would often break free of their mounting. The rails of the square profile permit an easier and more secure mounting of the casters, but the corners of the rails present potential discomfort to the shoulders, arms, hips, and legs of the user.